1. Field of the Invention
The present invention relates to a method for generating a multivariate analysis model expression for a processing apparatus, a method for executing a multivariate analysis of a processing apparatus, a control device of a processing apparatus and a control system for a processing apparatus.
2. Description of the Related Art
Various types of processing apparatuses are employed in semiconductor manufacturing processes. Processing apparatuses such as plasma processing apparatuses are commonly utilized during a film formation process through which a film is formed on a workpiece such as a semiconductor wafer or a glass substrate and an etching process through which the workpiece is etched. The individual processing apparatuses manifest inherent processing characteristics when processing a specific type of workpiece. Accordingly, the wafer processing is optimized by monitoring the processing characteristics of each apparatus or by predicting the processing characteristics of each apparatus.
For instance, Japanese Patent Laid Open Publication No. 06-132251 proposes a method for monitoring a plasma etching apparatus engaged in an etching operation. In this method, the relationships of the results of plasma spectroscopic analysis are ascertained in advance and changes in processing conditions (the pressure, the gas flow rates, the bias voltage, etc.) to the etching results (the uniformity, the dimensional accuracy, the shape, the selectivity with respect to the base film) and they are stored in a database so as to enable indirect monitoring of the processing results without having to directly inspect the wafer. If the monitored processing results do not clear the inspection criteria, NG information is output to the etching apparatus which is then allowed to modify the processing conditions or to halt the processing and, at the same time, the managing personnel are alerted.
In addition, Japanese Patent Laid Open Publication No. 10-125660 proposes a process monitoring method about a plasma processing apparatus. In this method, a model expression that correlates an electrical signal indicating the state of the plasma with the plasma processing characteristics is generated by processing test wafers prior to the actual process, and the detection value indicated by the electrical signal obtained while processing production wafers is used for substitution in the model expression to predict and diagnose the plasma state.
Japanese Patent Laid Open Publication No. 11-87323 proposes a method for monitoring a process by using a plurality of parameters in a semiconductor wafer processing system and an apparatus in which the method is adopted. In the method proposed in this publication, a plurality of process parameters are analyzed and changes occurring in the processing characteristics or in the system characteristics are detected based upon a statistical correlation of these parameters. The plurality of process parameters used in the method include light emission parameters, environmental parameters (the pressure, the temperature etc., inside the reaction chamber), RF power parameters (the reflectivity, the synchronizing voltage etc.) and system parameters (the specific system configuration and the control voltage).
However, with the technologies in the related art, a model expression is generated by analyzing various types of measurement data through a statistical method such as a multivariate analysis and the state and the processing characteristics of the processing apparatus are ascertained and monitored by using this model expression. Thus, the model expression generated in correspondence to a given processing apparatus cannot be directly utilized in conjunction with other processing apparatuses of the same type if the processing characteristics of the individual processing apparatuses are not consistent, e.g., if the characteristics of the individual sensors installed in the processing apparatuses are not completely uniform, which necessitates the model expression to be generated for each processing apparatus by taking in various types of measurement data and thus, the model expression generation is a labor-intensive, time-consuming process. In addition, each time the processing conditions are adjusted, the model expression must be generated by taking in various types of measurement data in correspondence to the specific set of processing conditions, which also makes the model expression generation a labor-intensive and time-consuming process.
An object of the present invention, which has been completed by addressing the problems discussed above, is to provide a method for generating a multivariate analysis model expression for a processing apparatus and a method for executing a multivariate analysis on a processing apparatus, through which a model expression generated in correspondence to a single processing apparatus can be utilized in conjunction with other processing apparatuses of the same type even when the processing characteristics or the processing conditions of the individual processing apparatuses are not consistent so as to reduce the onus of the model expression generation by eliminating the need to generate anew model expression for each processing apparatus from scratch and to enable an evaluation of the state of each processing apparatus without having to generate a new model expression in correspondence to each processing apparatus.